Everyday Mystery: Solving Foodborne Outbreaks

Every foodborne outbreak investigation starts with a clue. Here's how CDC and public health partners follow the evidence to solve food poisoning mysteries. Sierra, our national laboratory network, PulseNet, sees a spike in people sick with the same matching DNA strain of E. coli bacteria. Hmm, let's investigate. There are clusters of cases in Wyoming, Colorado, and Utah. Here, Colorado's state health department reports several people got sick after eating at a restaurant in Boulder. And this report is about an illness in Salt Lake City from around the same time. Colorado's report was for a grab-and-go store that chain sells pre-made Caesar salads with chicken, which all the sick people in Colorado ate. But wait a second, they don't have stores in Utah. After looking more into the Salt Lake City case, they do report eating a pre-made salad with chicken from a cafe. Wyoming also just said that several sick people reported eating pre-made salads with chicken. Our epidemiologic detective work found that pre-made salad with chicken is the one food item in common across the outbreak cases, but no common chain or brand. The culprit could be any one of the ingredients, like the lettuce mix, chicken, or even the dressing. Let's talk to the teams at FDA and USDA FSIS about next steps. Remind me what those stand for again? USDA FSIS is the U.S. Department of Agriculture Food Safety and Inspection Service. They oversee the safety of the meat and poultry we eat. FDA is the Food and Drug Administration. They oversee the safety of most of the other foods we eat. Both are federal regulatory agencies who can request that companies recall unsafe foods. FSIS said the chicken and the salads came from different places, so that rules out chicken as the culprit. FDA reviewed records for the lettuce mix and said Definitely Fresh Greens supplied a specific lettuce mix included in all the salads reported by sick people. Combined with our strong interview data for pre-made salads and the cases matching E. coli DNA fingerprints, this is really solid evidence that this lettuce mix is the source. Good investigating, Sierra. Let's get on the phone with FDA so we can talk to Definitely Fresh Greens as soon as possible. Definitely Fresh Greens said that the lettuce mix was used in many products and could still be in people's homes. FDA recommended they recall the products. So our next step is to post an outbreak notice with advice for consumers and businesses? Right. We'll need to describe what people can do to stop more people from getting sick. Great detective work, Sierra. CDC coordinates around 30 multi-state foodborne illness investigations in any given week. Solving foodborne outbreaks takes teamwork, strong science, and attention to every clue. Follow CDC on Facebook, Instagram, and X for the latest outbreak information.